1. To RNA sample add equal volume of acid phenol:chloroform (5:1, pH 4.7).
Phenol must be water-saturated first. Check pH. If pH is too high, lower
with acetic acid. Alternatively, lower the sample pH by adding 1/10 volume
of 2 M sodium acetate (pH 4).
2. Centrifuge for 10 minutes, and remove the aqueous phase to a new tube. The
aqueous phase contains RNA.
3. Add 1/10 volume of 5 M ammonium acetate and equal volume of isoproponal.
4. Mix well. Precipitate for at least 15 minutes at -20 °C.
5. Pellet RNA by centrifugation at maximum speed for at least 15 minutes
at 4 °C in a microcentrifuge.
6. Carefully remove supernatant. And wash with 70% ethanol.
9. Air dry and resuspend in a suitable
buffer. Store at -20 °C or -80 °C.